The salient advantage of wireless telecommunications over wireline telecommunications is that the user of the wireless terminal is afforded the opportunity to use his or her terminal anywhere. On the other hand, the salient disadvantage of wireless telecommunications lies in that fact that because the user is mobile, an interested party might not be able to readily ascertain the location of the user.
There are many techniques in the prior art for estimating the location of a wireless terminal. In accordance with some techniques, the location of a wireless terminal is estimated, at least in part, from measurements that are reported by the wireless terminal. The reported measurements are of signals measured by the wireless terminal that are transmitted by one or more base stations through their antennas and, in some cases, by Global Positioning System (GPS) satellites. Some techniques rely on signal-strength measurements, while some other techniques rely on time-based measurements, while still some other techniques rely on other types of measurements. In order for these estimation techniques to work, at least some of the transmitted signals have to be strong enough to allow for accurate measurement by the wireless terminal and for reliable processing by the particular technique.
A number of these techniques need to know which infrastructure antenna—as distinguished from the wireless terminal's antenna—radiates the signal that is received and decoded by the wireless terminal. An infrastructure antenna can be present in a variety of configurations; for example, it can be collocated with and coupled directly to a base station, or can be part of a distributed antenna system (DAS), or can be part of another type of antenna system (e.g., a repeater, etc.). In wireless telecommunications systems without distributed or repeater antennas, determining which infrastructure antenna radiates which signal is generally straightforward because each signal is uniquely associated with one infrastructure antenna. Therefore, the decoding and identification of a signal is tantamount to the identification of the infrastructure antenna that radiated the signal.
In wireless telecommunications systems that comprise distributed antenna systems, however, the decoding and identification of a signal does not inherently indicate which infrastructure antenna radiated it. Therefore, the need exists for a technique for estimating information about distributed antenna systems that are present within a wireless telecommunication system, whereupon the information can be used for estimating the location of a wireless terminal or for other purposes.